It's not quite a Pinky and the Brain scenario, but researchers from MIT and several European universities have spliced a human gene responsible for speech and language into mice — a bit of biological uplift that made the mice smarter in certain ways.

But this new experiment is unique in that (1) it's at the genetic level and (2) it's the first to assess how partially "humanizing" the brains of mice affects key cognitive functions. In this case, hundreds of mice were genetically engineered to carry the human version of FOXP2, a gene linked to speech and language.

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Researchers Ann Graybiel and her colleagues found that this genetic change affected the mouse brain's striatum and related cortico-basal ganglia circuits — areas known to be essential for motor and cognitive behaviors such as speech and language capabilities in humans.

For the study, the super-mice were trained to find chocolate milk in a maze. The genetically humanized mice learned the route just as well by seven days as regular mice did by 11. Not bad. MIT News reports:

The first phase of this type of learning requires using declarative memory, or memory for events and places. Over time, these memory cues become embedded as habits and are encoded through procedural memory — the type of memory necessary for routine tasks, such as driving to work every day or hitting a tennis forehand after thousands of practice strokes.

Using another type of maze called a cross-maze, [the researchers] were able to test the mice's ability in each of type of memory alone, as well as the interaction of the two types. They found that the mice with humanized Foxp2 performed the same as normal mice when just one type of memory was needed, but their performance was superior when the learning task required them to convert declarative memories into habitual routines. The key finding was therefore that the humanized Foxp2 gene makes it easier to turn mindful actions into behavioral routines. [emphasis added]

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In other words, the FOXP2 gene accelerates learning in mice by enhancing the transitions from declarative to procedural memory.

And by isolating this one gene, the researchers are not only shedding light on its function, but also on how it may have led to the evolutionary changes that resulted in the unique capabilities of the human brain.